1. Field of the Invention
The present invention relates to a catalyst block penetrated by a number of parallel passages for effecting catalytic conversion reactions in an exhaust gas flowing through the passages.
2. Description of the Prior Art
Prior art catalyst blocks are normally provided with passages having a honeycombed cross section. The passages are generally distributed in several rows above one another. The manufacture of such catalyst blocks is expensive. In addition, the passages with a honeycomb cross section quickly become clogged, especially when the exhaust gases contain large quantities of dust, and as a result, the catalyst block becomes unusable. A further disadvantage of such known designs is that on account of the honeycomb shape and the rapid clogging of passages, there are significant pressure losses in the exhaust gas flowing through.
Catalyst blocks have also been proposed in which a number of catalyst plates are arranged in a frame. Assembly of the catalyst plates in such a frame represents an additional operational step. Examples of prior art relating to catalysts are found in German Pat. No. DE-PS 25 12 410 which corresponds to U.S. Pat. No. 4,087,250, entitled "Apparatus for Removing Nitric Oxides from Processing Exhaust Gases", U.S. Pat. No. 4,081,511, entitled "Process for Removing Nitric Oxides from Processing Exhaust Gases", and German Laid Open Patent Application No. DE-OS 25 12 409, all of which are incorporated by reference as if fully set forth herein.